Democrats could gain from a possible “wave election” on Nov 3, which may weaken Trump’s control of Congress and force more oversight, compromise and scrutiny.

The House looks easier for Democrats to win than the Senate. They need three seats for the House, but four for the Senate, where the filibuster and 60-vote rule matter.

If Democrats win one or both chambers, they could block Trump’s bills, launch investigations and slow nominees. Trump can still act through executive orders and vetoes.

AI generated WASHINGTON – In his second term, US President Donald Trump has so far benefited from his Republican Party holding majorities in both houses of Congress, as he did in the top half of his first turn in the White House.

When one party controls both the presidency and Congress, ambitious legislation can become law, as evidenced by the tax-cut measures enacted under Trump in 2017 and 2025.

And with party faithful running congressional committees, a presidential administration is insulated, to some extent, from tough scrutiny from such bodies.

Now, public disapproval of Trump’s job performance threatens to bring the one-party Republican government to a crashing halt in the Nov 3 congressional elections.

A “wave election” that breaks in favour of the Democrats would, in Trump’s final two years in the White House, expose his administration to greater oversight and force it to accept compromise if it wants to enact legislation. At the same time, there’s a lot a president can do without Congress.

Trump already has tested the bounds of a president’s power by issuing expansive executive orders, including some that have been struck down by the courts, and waging war against Iran without congressional authorisation. What’s a wave election?

There’s no precise definition, but the term is used to describe when a political party makes major gains in the House of Representatives, the Senate or both.

Generally speaking, congressional wave elections have occurred at the midpoint of a president’s four-year term – when the president isn’t on the ballot – and have usually benefited the party that doesn’t occupy the White House, which right now is the Democratic Party. In a wave election, the closest races can tend to break all in the same direction. How many seats are being contested in 2026?

All 435 House of Representatives seats and 35 of the 100 Senate seats. Republicans hold a 218 to 214 edge in the House. There are two vacant seats in the House. In the Senate, Republicans have a 53-to-47 advantage.

All 35 races are for full six-year terms except for special elections in Florida and Ohio to serve out terms that will expire at the end of 2028. Can Democrats win control? The Democrats are better positioned to win control of the House than the Senate.

Democrats need a net gain of just three seats for a majority in the House and have over-performed in special elections held since Trump returned to the presidency in January 2025. The Senate poses a steeper challenge.

Democrats need a net gain of four seats for a 51-seat outright majority because Vice-President J.D. Vance could break any 50-50 split in favour of Republicans.

Democrats would likely have to retain all or almost all of their 13 current seats that are being contested, including in the politically competitive states of Michigan, Georgia and New Hampshire.

Of the 22 states with Republican-held seats on the ballot, all but Maine and North Carolina favoured Trump by more than 10 percentage points in the 2024 election. Democrats would need to flip at least two of those double-digit Trump states. That looked unlikely at the start of the campaign cycle but is more realistic now.

Strong candidate recruitment and an anti-Trump political environment have made Democrats highly competitive in a raft of traditionally Republican-leaning states such as Alaska, Iowa, Kansas, Ohio and Texas. Why do waves happen?

One theory is that anger energises citizens, so those opposed to the President and his policies are more motivated to turn out at the polls than those happy with the status quo.

The backlash can be severe: Since the end of World War II, the president’s party on average has suffered a net loss of about 25 House seats and 3.5 Senate seats in midterm elections. What are polls and prediction markets saying? Polls suggest that most of the public is deeply dissatisfied with the direction of the country and with the President.

Trump’s approval rating – 37% in a New York Times average of daily polls as at Oct 30 – is one of the lowest of any president since World War II and comparable to Republican George W. Bush’s 38% approval rating in a Gallup Poll on Election Day 2006, when Democrats won majorities in both the House and Senate for the final two years of Bush’s presidency. The less popular the president, the more seats his party tends to lose.

Polls show Democrats leading Republicans in voter enthusiasm and in a generic congressional ballot question that asks voters which party they support in the upcoming election.

Prediction markets Polymarket and Kalshi point to a Democratic sweep, giving the party better than 90% odds of winning control of the House and about a two-thirds chance of securing a Senate majority. What would Democratic victories in Congress mean for legislation?

Even if control of only one chamber flips, Trump’s ability to get Congress to pass legislation opposed by Democrats would be thwarted.

A Bill must be approved by both the House and Senate before it is sent to the president’s desk to be signed into law or vetoed. So a united Democratic majority in either chamber would be able to block any Bill.

For those same reasons, control of just one chamber wouldn’t enable the Democrats to pass legislation on their own.

Their ability to do so would be limited even if they take both the House and Senate.

That’s because for most legislation, Senate approval requires a supermajority, which the Democrats are unlikely to achieve in this election.

In the Senate, members enjoy a privilege known as the filibuster, which is the prerogative to demand never-ending debate to thwart legislation.

It takes 60 votes in the 100-seat Senate to end a filibuster – and thus 60 votes to pass most legislation.

With control of both houses of Congress, the Democrats could get around the filibuster using a process called budget reconciliation that’s permitted for Bills relating to spending, taxes and the federal debt limit, which is a cap established by Congress on US government borrowing.

First, the House and Senate must agree to a budget resolution, which sets overall spending and revenue targets.

Then, Bills advanced in the name of “reconciling” tax and spending practices with that budget resolution need only a simple majority vote to win approval in the Senate.

It’s this process that Republicans, then in full control of Congress, used to pass tax cuts in 2017 in Trump’s first term and again in 2025 in his second. Of course, Trump can veto any Bill passed by Congress.

To overcome a presidential veto requires a two-thirds supermajority in both the House and Senate, improbable goals for Democrats in this election.

At the same time, were Trump to veto Bills with significant popular support, for example, Bills aimed at addressing issues of affordability that were top of mind for voters going into the election, he would risk further tanking his approval rating.

Options for such Bills would include a reversal of the 2025 tax law’s spending reductions to Medicaid, a government health insurance programme primarily for the poor, and a revival of enhanced subsidies to help people pay for health insurance.

Given a willingness to compromise, significant legislation can become law even when one party has the White House and the other controls one or both chambers of Congress.

Examples include a Social Security rescue package in 1983, a major tax overhaul in 1986, and sweeping changes to the welfare system in 1996. Would Democratic victories in Congress mean new investigations into Trump?

Trump and his administration would likely face new or re-energised investigations by congressional committees that would switch to Democratic control.

Potential targets for probes include the Trump family’s stock trading and cryptocurrency ventures, private companies’ funding of Trump’s White House ballroom project, the administration’s immigration enforcement policies, and its handling of files related to the late sex offender and financier Jeffrey Epstein. However, the power of congressional investigations has important limits.

Congressional committees can issue subpoenas to try to compel private citizens, businesses or government officials to produce documents or testify, and committees can cite those who refuse for criminal contempt of Congress, which is punishable by a fine and imprisonment for up to 12 months.

But while Congress can refer officials to the Justice Department for criminal prosecution, it cannot bring charges itself.

The Justice Department, which is part of the executive branch, has discretion over whether to act on a referral and holds the exclusive power to bring federal criminal charges. Is Trump’s impeachment a possibility?

A Congress run by Democrats could pursue a third impeachment of Trump, but it is not a focus of the Democrats’ messaging. The impeachment process starts in the House.

If the House approves articles of impeachment against the president with a simple majority, the president is impeached, though not yet removed from office.

The Senate then holds a trial. If the Senate votes to convict by a two-thirds majority, the president is removed from office.

Trump was impeached twice in the second half of his first term, after Democrats won control of the House in the 2018 midterms.

In December 2019, the House impeached him on charges of abuse of power and obstruction of Congress.

The House alleged that the President conditioned military aid to Ukraine on its government opening investigations into the President’s political rival Joe Biden and Biden’s son Hunter.

The House impeached Trump a second time in January 2021, charging him with inciting an insurrection in connection with the Jan 6 attack on the US Capitol, which delayed the certification of Biden’s victory over Trump in the 2020 presidential election. Neither impeachment led to a Senate conviction.

If Democrats pursue another impeachment, they’re unlikely to successfully remove Trump from office because of the Senate’s requirement of a two-thirds majority vote to secure a conviction. Even if Democrats make significant gains in the chamber, it’s highly improbable they will reach that threshold.

In any case, party leaders have downplayed an impeachment scenario during the 2026 election campaign and urged their candidates to run on a platform of lowering everyday living costs and easing economic burdens for working families. How would Trump’s ability to make appointments be affected?

A Democratic-run Senate could stall or block Trump’s judicial and executive nominees.

Among the presidential appointees that require Senate confirmation are Cabinet members, Supreme Court and federal judges, ambassadors and the heads of government agencies and commissions.

Republican control of the Senate enabled Trump to win confirmation – just barely – of a number of controversial figures, including Pete Hegseth as defence secretary, Robert F. Kennedy Jr. as health and human services secretary, and Kash Patel as Federal Bureau of Investigation director.

There’s been less turnover among officials in his second administration than in his first, but Trump would have considerably less leeway filling vacancies if he needs Senate Democrats to okay his picks. What can Trump do without Congress? The president can enact significant policy changes without Congress through executive action.

Trump has ordered military strikes on Iran, imposed and removed tariffs, fired large swaths of the federal workforce, withdrawn the US from the World Health Organization and the 2015 international climate treaty the Paris Agreement, and seized and extracted long-time Venezuelan President Nicolas Maduro to the US – all without legislative action from Congress.

Ches McDowell, managing partner of Checkmate Government Relations and a lobbyist with close ties to the Trump administration, said Trump will remain the centre of power in Washington regardless of the outcome of the midterms.

“We’ve been telling clients, the administration is still going to be the primary body to get anything done, no matter if the Democrats take the House and the Senate,” McDowell said at a Bloomberg Government executive dinner roundtable on Oct 21. Are Republicans worried about losing their majorities?

Yes, though party leaders rarely convey worry publicly because they don’t want to dispirit their voters and donors.

Speaker of the House Mike Johnson, a Republican, has repeatedly said his party will “defy history” and keep control of the chamber.

Senator Tim Scott, who leads the Senate Republicans’ campaign organisation, told reporters on Sept 30 that “we will hold the Senate majority, without question,” though he said there are a “record number” of toss-up Senate races and acknowledged tight races in traditionally Republican-leaning states such as Kansas and Nebraska.

Trump, in a rare acknowledgement of his weak standing with voters, said on Sept 30 that he’s “done a very bad job of explaining how good the country is doing”.

Senator Thom Tillis, a North Carolina Republican who’s not seeking re-election, said in his book released on Oct 6 that he expected a “bloodbath” for his party on Nov 3.

Republican super political action committees (PACs) are spending much more to defend their own states and districts, many of which strongly favoured Trump in the 2024 election, than they are on contesting Democratic-held seats.

In early October, the leading super-PAC defending the Senate Republican majority pulled out of North Carolina, where Democrats are likely to win a seat from Republicans, and instead shifted resources to races in Republican-leaning Kansas, Mississippi and South Carolina. Do Republicans have any advantages?

Yes. In recent months, seven states – Alabama, Florida, Louisiana, North Carolina, Ohio, Tennessee and Texas – have adopted a more Republican-skewing electoral district map.

Some acted after the US Supreme Court in April 2026 curtailed the use of the Voting Rights Act to draw predominantly black and Hispanic districts.

However, a Democratic “wave” could significantly limit the gains Republicans had expected to make through redistricting. Also, Democrats retaliated against Republican-led redistricting across the country with a partisan map of their own in California, and they’re likely to wrest one seat in Utah from Republican control under a new court-approved map.

Another Republican advantage: The party’s PAC generally are more cash-flush than their Democratic counterparts.

The pro-Trump MAGA Inc super-PAC had more than US$415 million (S$531 million) in the bank as at early September, and the Republican National Committee had a cash advantage of more than US$100 million over the Democratic National Committee.

However, super-PACs pay higher advertising rates than federal candidates, and a favourable political environment can neutralise the opposition’s cash advantage. BLOOMBERG